<!DOCTYPE html>    
<html lang="zh-Hans">    
<head>    
    <meta charset="UTF-8">    
    <meta name="viewport" content="width=device-width, initial-scale=1.0">    
    <meta http-equiv="X-UA-Compatible" content="ie=edge">    
    <title>提示框</title>    
    <style>    
        body {    
            background: lightgrey;    
            position: relative;    
            height: 100vh;    
        }    
        .box {    
            width: 500px;    
            height: 300px;    
            background: white;    
            border-radius: 8px;    
            position: relative;    
            margin: 0 auto;    
            top: 150px;    
        }    
        .box-title {    
            width: 490px;    
            height: 40px;    
            position: absolute;    
            top: 5px;    
            left: 5px;    
            border-radius: 6px;    
            background-color: #167bef;    
            color: white;    
        }    
        .box-title h3 {    
            float: left;    
            font-size: 18px;    
            margin: 0 0 0 10px;    
            line-height: 40px;    
        }    
        .box-title a {    
            float: right;    
            height: 20px;    
            width: 20px;    
            margin: 10px 10px 0 0;    
            line-height: 20px;    
            font-size: 20px;    
            text-decoration: none;    
            color: white;    
            display: block;    
            text-align: center;    
            border-radius: 50%;    
            background-color: rgba(255, 255, 255, 0.2);    
        }    
        .box-content {    
            position: absolute;    
            top: 50px;    
            left: 10px;    
            right: 10px;    
            bottom: 60px;    
            overflow-y: auto;    
            padding: 10px;    
            color: #333;    
            font-size: 16px;    
        }    
        .box-button {    
            position: absolute;    
            bottom: 10px;    
            left: 10px;    
            right: 10px;    
            text-align: right;    
        }    
        .box-button input {    
            margin-left: 10px;    
            padding: 10px 20px;    
            font-size: 16px;    
            cursor: pointer;    
        }    
    </style>    
</head>    
<body>    
<div class="box">    
    <div class="box-title">    
        <h3>系统提示</h3>    
        <a href="#">×</a>    
    </div>    
    <div class="box-content">亲，确定这么做吗？</div>    
    <div class="box-button">    
        <input type="button" value="取消">    
        <input type="button" value="确定">    
    </div>    
</div>    
</body>    
</html>